symbiosis

Deep research

Generated by just research-trait; source: research/traits/ecology/symbiosis-deep-research-falcon.md

# Curation report: microbial symbiosis (`traitmech:000040`)

## Executive curation recommendation

The supplied reviewed class should remain an **umbrella ecological-lifestyle trait**: a microorganism lives in persistent physical association with a host or partner, while the interaction outcome—mutualism, commensalism, or parasitism—is represented separately. Recent synthesis supports a continuum of outcomes but also shows that host finding, attachment, competition, immune accommodation, physiological adaptation, and persistence are shared mechanistic stages across that continuum. Therefore, no single gene or pathway is either necessary or sufficient for “symbiosis” across microorganisms. The graph should consist of **taxon-qualified alternative mechanism modules**, not one universal linear pathway. (wiesmann2023originsofsymbiosis pages 6-8, wiesmann2023originsofsymbiosis pages 1-2)

The strongest additions are: (i) a host-specific adhesin/alternative-secretion module in *Lactiplantibacillus plantarum*–*Drosophila*; (ii) an *mglB*–type-IV-pilus motility module in bee-associated *Snodgrassella*; (iii) a Nod-factor/NFR signaling and root-exudate module in *Lotus japonicus*–rhizobia; and (iv) an ApGLNT1-controlled metabolic-integration module in the pea aphid–*Buchnera* system. These are supported by live imaging, mutant or knockdown experiments, host mutants, serial passage, and competition assays. (gutierrezgarcia2024aconservedbacterial pages 6-7, gutierrezgarcia2024aconservedbacterial pages 9-13, meng2024identificationofthe pages 1-2, duncan2023cooptionofa pages 7-8, tao2024nitrogenandnod pages 1-2)

| Proposed mechanism / edge module | Strongest model system | Evidence design | Confidence / curation recommendation | Key quantitative result | DOI |
|---|---|---|---|---|---|
| SRRP adhesins + aSec secretion system -> stable host-specific foregut colonization | *Lactiplantibacillus plantarum* in *Drosophila melanogaster* gut | Live imaging of single cells, experimental evolution, colonization-island loss mutant, CRISPRi of adhesins | **High; curate as taxon-specific direct edge** | Stable wild-type colonization of ~20,000-50,000 CFU per gut; high-affinity binding diffusion coefficient 0.001 µm2/s versus 0.10 µm2/s for transient binders; colonization-island loss increased diffusion to 0.122 µm2/s; CRISPRi colonization defect ****P<0.0001 (gutierrezgarcia2024aconservedbacterial pages 6-7, gutierrezgarcia2024aconservedbacterial pages 3-4, gutierrezgarcia2024aconservedbacterial pages 9-13) | 10.1126/science.adp7748 |
| *mglB* allele / type IV pili-dependent motility -> increased colonization in non-native host | *Snodgrassella* from *Bombus terrestris* serially passaged in *Apis mellifera* | ARTP mutagenesis, in vivo serial passage, gnotobiotic bees, competition assays | **High; curate as taxon-specific direct edge** | Mutant alleles in the mutual gliding locus out-competed the ancestral strain in the non-native honeybee gut but not in the native host; effect interpreted as altered type IV pili-dependent motility (meng2024identificationofthe pages 1-2) | 10.1186/s40168-024-01813-0 |
| Rhizobial Nod factors -> NFR1/NFR5 signaling -> altered root exudate composition -> altered microbiota assembly | *Lotus japonicus* with rhizobial symbionts | Host mutant comparison (*nfr5*, *nfr1/nfre*, *chit5*), metabolomics, microbiome profiling across nitrogen states | **High for plant-side causal chain; curate as taxon-specific direct edge** | Distinct “starved, symbiotic, or inorganic” nitrogen states produced different root/rhizosphere microbiomes; Nod-factor-signaling mutants had altered community assembly and exudate profiles (tao2024nitrogenandnod pages 9-11, tao2024nitrogenandnod pages 1-2) | 10.1038/s41467-024-47752-0 |
| Rhizobial nitrogenase: N2 -> NH4+ and plant photosynthate/carbon exchange supports persistent symbiosis | Legume-rhizobium root nodules | Integrative physiological/genetic review drawing on split-root, metabolomic, transcriptomic, and mutant literature | **Moderate-High; curate only at generic process level unless adding species-specific supporting primary data** | No single effect size extracted here, but source states bacteria reduce N2 to NH4+ and plant supplies photosynthates/dicarboxylates; nitrogen demand and sugar allocation tune nodule function and senescence (lepetit2023controlofthe pages 1-2) | 10.3389/fpls.2023.1114840 |
| Host ApGLNT1 glutamine transporter + arginine feedback -> metabolic integration with *Buchnera* amino-acid biosynthesis | *Acyrthosiphon pisum*–*Buchnera aphidicola* | Functional transporter characterization, modeling, comparative phylogeny, metabolite concentration comparison | **High; curate as taxon-specific direct edge** | Arginine IC50 values for GLNT1 orthologs are within/near phloem sap arginine range of 4.4-15.2 mM; aphid hemolymph arginine was insufficient to inhibit ApGLNT1, whereas hemolymph glutamine approached saturating levels (duncan2023cooptionofa pages 7-8) | 10.1073/pnas.2308448120 |
| Conserved host-association module: chemotaxis/host sensing + TCS + biofilm + secretion systems + immune evasion -> persistent host association across symbiosis continuum | Cross-system review emphasizing *Pseudomonas*, *Sinorhizobium*, *Brucella*, *Agrobacterium* and other plant/animal associates | Comparative review of shared mechanisms; includes mutant examples for TCS/biofilm systems but mostly umbrella synthesis | **Moderate; curate as umbrella background only, not as a single universal edge** | Review identifies five shared features across pathogenic, commensal, and mutualistic bacteria; no unified cross-taxon effect size, though individual TCS mutants show impaired symbiosis/virulence in cited systems (wiesmann2023originsofsymbiosis pages 6-8, wiesmann2023originsofsymbiosis pages 1-2) | 10.1093/femsre/fuac048 |


*Table: This table ranks the strongest candidate mechanism modules for curating microbial symbiosis (traitmech:000040), separating direct taxon-specific causal edges from broader cross-system umbrella claims. It is useful for deciding which nodes and edges are ready for TraitMech curation versus which should remain as background or warning-level context.*

## 1. Trait scope and boundaries

### Intended phenotype

- **Trait:** `traitmech:000040`—quote and retain this identifier verbatim.
- **Category:** ECOLOGY; **term kind:** CLASS; **mapping:** REVIEWED.
- **Parent:** `METPO:1000059`.
- **Operational meaning:** capacity or realized lifestyle of maintaining a spatially persistent association with a host or partner organism.
- **Observable assays:** repeated recovery after washout or transfer, stable CFU burden, microscopy showing niche-localized cells, vertical transmission, long-term intracellular residence, stable biofilm/adhesion, or organ-specific colonization.
- **Outcome is not the trait itself:** benefit, neutrality, or harm to the host should be encoded as context or a child interaction mode. Pathogens, commensals, and mutualists can use homologous colonization machinery. (wiesmann2023originsofsymbiosis pages 1-2)

### Boundary cases

| Case | Curation decision |
|---|---|
| Transient contact, chemotaxis toward a host, or short-lived attachment | **Insufficient alone.** These can be upstream steps but do not establish persistence. |
| Environmental co-occurrence or correlated abundance | **Exclude** unless physical association and persistence are demonstrated. |
| Cross-feeding between spatially separated organisms | **Exclude from this trait alone**; curate as metabolic interaction unless persistent physical association is also shown. |
| Biofilm formation on an abiotic surface | **Not symbiosis by itself.** Include only when it causally supports association with a living partner. |
| Infection/pathogenesis | **Include** when persistent physical host association is present; pathogenic outcome is a contextual subtype, not an exclusion. |
| Microbiome membership detected once by sequencing | **Weak evidence.** Presence does not establish attachment, residence, or activity. |
| Obligate intracellular endosymbiosis | **Clearly included**, but genome reduction or vertical transmission should not be generalized to all symbioses. |
| Facultative or condition-dependent association | **Included** if persistence occurs under the stated host/environmental conditions. |

A useful graph distinction is: `host encounter → recognition/migration → attachment or invasion → immune accommodation/competition → host-conditioned metabolism → persistence`. Only the final realized association should point directly to `traitmech:000040`; upstream mechanisms should point through colonization or persistence nodes.

## 2. Candidate nodes grouped by type

Identifiers below are deliberately conservative. Organism-specific genes and incompletely verified structures remain label-only rather than receiving invented CURIEs.

### A. Trait and biological-process nodes

- `traitmech:000040` — symbiosis.
- `METPO:1000059` — supplied parent trait.
- Host colonization — label-only candidate.
- Stable host attachment — label-only candidate.
- Host-specific niche recognition — label-only candidate.
- Biofilm formation — candidate GO-grounded process; verify the exact GO term during ingestion.
- Chemotaxis — candidate GO-grounded process; verify exact CURIE.
- Type-IV-pilus-dependent motility — candidate GO-grounded process; verify exact CURIE.

Showing the first 60 of 223 lines of findings; the linked file also carries the run's front matter and the prompt it was given — read the full report.